Question

This reaction is used to produce ammonia commercially.

3H2 (aq) + N2 (aq) → 2HN3 (g)

If 1.40 g of nitrogen is used in the reaction, what mass of hydrogen is needed?

Answer 1

This reaction is used to produce ammonia commercially.

$$3 H _ {2} (a q) + N _ {2} (a q) \rightarrow 2 H N _ {3} (g)$$

If 1.40 g of nitrogen is used in the reaction, what mass of hydrogen is needed?

Answer:

We are given:

$$m (N _ {2}) = 1.4 g$$

Thus, amount of substance of nitrogen is:

$$v (N _ {2}) = \frac {m (N _ {2})}{M (N _ {2})}$$

Where

$M(N_{2})$ is molar mass of nitrogen;

$$M (N _ {2}) = 2 * 14 = 28 \, g/mol$$

So:

$$v (N _ {2}) = \frac {1.4}{28} = 0.05 \, mol$$

As it is seen from reaction equation:

$$\frac {v (N _ {2})}{v (H _ {2})} = \frac {1}{3}$$

Thus:

$$v (H _ {2}) = v (N _ {2}) * 3 = 0.15 \, mol$$

molar mass of hydrogen;

$$M (H _ {2}) = 2 * 1 = 2 \, g/mol$$

Thus:

$$m(H_2) = v(H_2) * M(H_2) = 0.15 * 2 = 0.3 \, g$$

Answer: $0.3 \, g$

References:

1) http://en.wikipedia.org/wiki/Molar_mass#Molar_masses_of_compounds